1. Field of the Invention
The present invention relates to a liquid crystal display (LCD), and more particularly to a peripheral circuit disposed on an active device array substrate of an LCD.
2. Description of Related Art
Nowadays, multimedia technologies have been well developed, which mostly results from the progress of semiconductor devices and display apparatuses. Among various displays, LCDs with superior features such as high definition, great space utilization, low power consumption and no radiation have gradually become the mainstream of the market.
Taking a thin film transistor LCD (TFT-LCD) module for example, it is mainly constituted by an LCD panel and a backlight module. The LCD panel usually includes a thin film transistor array substrate (TFT array substrate), a color filter substrate (C/F substrate) and a liquid crystal layer interposed therebetween. On the other hand, the backlight module provides a planar light source for the LCD panel, such that the LCD module is able to perform a display function.
The TFT array substrate can be divided into a display region and a peripheral circuit region. A plurality of pixel units is disposed in arrays on the display region, and each of the pixel units includes a TFT and a pixel electrode connected to the TFT. Moreover, a plurality of scan lines and a plurality of data lines are disposed on the peripheral circuit region and the display region. The TFT of each of the pixel units is controlled by the corresponding scan line and data line.
After a manufacturing process of the TFT array substrate is completed, an electrical inspection is often performed on the pixel units on the TFT array substrate, so as to determine whether the pixel units are operated normally. When the pixel units are not able to be operated in a normal manner, defective components (such as the TFT or the pixel electrode) or the circuit can be repaired.
The electrical inspection is usually implemented on the peripheral circuit with use of probes. In particular, the peripheral circuit has a plurality of test pads electrically connected to the scan lines and the data lines. After each of the test pads is contacted by the probes, a test signal is delivered, and thereby it is likely to observe if each of the pixel units is normally operated. Nevertheless, the LCDs are miniaturized and characterized by high resolution, such that the pixel units tend to be densely disposed in the LCDs. Hence, the width of the test pads is reduced little by little. If the width of the test pads is less than the dimension of the probes, it would be unlikely for the probes to precisely detected each of the scan lines or data lines. In other words, one single probe may contact two adjacent test pads simultaneously. As such, defects of the active device array cannot be discovered and rectified.